Episode 39 of The Trigan Empire
The House of the Five Moons
aka In de greep van het kwaad / De dubbelganger (Dutch title)
Gripped by Evil / The Look-alike (Dutch title, translated)
Written by Mike Butterworth
Illustrated by Don Lawrence
It is reprinted in Volume 10 of The Trigan Empire—The Collection (the Don Lawrence Collection).
It is reprinted in Volume 4 of The Rise and Fall of the Trigan Empire (Rebellion).
Plot summary (Dutch)
MediaFire via British Comics Compilations